| Project/Area Number |
16560020
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thin film/Surface and interfacial physical properties
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| Research Institution | University of Tsukuba |
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Principal Investigator |
SHIRAISHI Kenji University of Tsukuba, Graduate School of Pure and Applied Physics, Associate Professor, 大学院・数理物質科学研究科, 助教授 (20334039)
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| Co-Investigator(Kenkyū-buntansha) |
AKIYAMA Toru Mie University, Department of Engineering, Research Assistant, 工学部, 助手 (40362363)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | LSI / Silicon / Semiconductor / Defects / Impurity / Insulating films / High-k dielectrics / Interface Reaction / 量子論 / 理論 / 第一原理計算 / 界面 / 欠陥 / シリコンナノ構造 / Si / SiO_2界面 / High-k絶縁膜 / Si界面 / トランジスタ特性 / HfO_2 |
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| Research Abstract |
In this project, we have investigated the physical properties of defects in high-k HfO_2 dielectrics and the formation process of interface layer SiO_2 located between high-k dielectrics and Si substrates. The main results are as follows.
(1)Based on the ionic characteristic of HfO_2, we have discussed the mechanism of Fermi level pinning observed at the interface between p+poly-Si gates and high-k HfO_2 dielectrics. As a result, we have found that the oxygen vacancy formation accompanied by the partial oxidation of poly-Si gates becomes endothermic due to the energy gain of electron transfer from oxygen vacancy level in Hf02 to p+poly-Si gates, and this reaction generates the interface dipoles and Fermi level of p+ poly-Si gates elevates. Further, this reaction continues until the energy gain of this reaction decreases to zero at the pinning position.
(2)We have investigated the N incorporation effect by the first principles calculations. We have found that N incorporation deactivate the oxygen vacancy level that is located just above the conduction band bottom of Si and can be considered as a important leakage path of HfO_2 gate dielectrics. This deactivation originates from the Coulomb interaction of N impurities.
(3)We have considered the formation process of interfacial SiO_2 by the first principles calculations. We have found that the strain near the interface strongly affects the formation process of SiO_2. Since the strain release process of the formation of interfacial SiO_2 is much different from the usual silicon thermal oxidation, the formed interfacial SiO_2 characteristics should be different from ordinary thermally grown SiO_2.
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